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1 Study Rationale and Overview RATIONALE Did participation in the U.S. nuclear weapons test program harm the mili- tary personnel involved? Reported effects range from nonfatal skin and eye con- ditions to cancers both incident and fatal. The epidemiologic study presented in this report addresses mortality alone. It examines whether participants died sooner than nonparticipants or were more likely to die from specific causes such as leukemia. From the results, one may deduce but not establish the extent to which radiation exposure may have caused the different mortality rates, if any, in the two groups. This study, however, does not address questions concerning the relationships between test participation or radiation exposure and nonfatal adverse health effects. BACKGROUND In 1976, a veteran asserted that his acute myelocytic leukemia was related to his participation in Shot SMOKY, a test in the 1957 Operation PLUMBBOB series at the Nevada Test Site. In response, the Centers for Disease Control (now Centers for Disease Control and Prevention) mounted an epidemiologic study of military personnel who had attended this test and found more than the expected number of leukemia cases among participants (Caldwell et al., 1980; Caldwell et al., 1983~. This generated concern that participation in the atmospheric testing program may have adversely affected health. In 1981, the Medical Follow-up Agency (MFUA) of the National Academy of Sciences designed a study to evaluate the question of increased mortality among test participants beyond those present at Shot SMOKY. MFUA researchers, s
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6 THE FIVE SERIES STUDY working with the Defense Nuclear Agency,l chose to study five of the 19 U.S.- conducted atmospheric test series. These five Operations GREENHOUSE (1951), UPSHOT-KNOTHOLE (1953), CASTLE (1954), REDWING (1956), and PLUMBBOB (1957:represent tests at the Pacific and Nevada test sites, sub- stantial numbers of personnel from each of the branches of military service, and different kinds of nuclear devices. In that study (Robinette et al., 1985), the mor- tality experience of approximately 49,000 veterans identified by the Defense Nu- clear Agency (DNA) as having participated in at least one of the five selected test series was compared to mortality rates in the U.S. male population. In 1989, the Defense Nuclear Agency (DNA) informed MFUA that the data it had provided-on which all MFUA analyses were based incorrectly identi- fied many members of the participant cohort. MFUA (with the support and con- currence of the congressional Office of Technology Assessment tGelband, 1992], the General Accounting Office tGAO, 1992], members of Congress, and Department of Defense staff) decided that the published study results should be withdrawn from discussion pending correction of the possibly substantial errors in participant group identification and subsequent reexamination of the data. At the request of the DNA, MFUA has redone the Five Series Study. We present the results of that study in this report. In addition to the essential clarification of participant cohort membership, which resulted in a substantial increase in the number of participants, the new Five Series Study also includes a referent group of military personnel who did not participate in nuclear tests, a design element that enhances its usefulness. We took advantage, also, of the additional 11 years of mortality experience that had accrued since the completion of the first study. In July 1992, the Institute of Medicine established an eight-member com- mittee representing expertise in epidemiology, biostatistics, radiation biology, radiation medicine, military records, and health physics to advise MFUA staff. This committee provided oversight concerning methods of exposure-data ascer- tainment, mortality assessment, referent group selection, radiation effects on human health, consideration of carcinogenesis mechanisms, statistical methods, and military records use. The committee was chaired for many years by Clark Heath, Jr., M.D., then vice president for epidemiology and surveillance research at the American Cancer Society. Committee member Harvey Checkoway, Ph.D., professor, Departments of Environmental Health and Epidemiology, at the Uni- versity of Washington in Seattle, assumed the chair recently when Dr. Heath accepted a staff position with the Radiation Effects Research Foundation in Hi- roshima, Japan (its affiliation with the National Research Council makes him ineligible to serve as a committee member). 1 The organizational locus of the Nuclear Test Personnel Review Program within the Department of Defense has been the Defense Nuclear Agency (until June 1996), the De- fense Special Weapons Agency (until October 1998), and, currently, the Defense Threat Reduction Agency.
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STUD YRATIONALE AND OVERVIEW 7 OVERVIEW This study addresses one main question: Did participation in at least one of the five selected nuclear weapons test series change the risk of death for the military personnel involved? We statistically compared the mortality experience ofthese 68,168 participant individuals with: · a referent group of 64,781 veterans chosen to be comparable to partici- pants with respect to age, paygrade, branch of service, time of military service, and type of assigned military unit but who were not participants in any nuclear test; and · the U.S. white male population. In discussing the Five Series Study findings, we compare them with the findings of studies that examined mortality among other groups of military vet- erans who participated in nuclear tests. The Defense Nuclear Agency defined membership in the participant group (see Chapter 5~. We constructed a referent group, beginning with a list of DNA- identified comparable military units (see Chapter 6~. Using records of the De- partment of Veterans Affairs and the National Archives and Records Admini- stration (see Chapter 4), we identified individuals from the participating and referent units and deaths among these individuals. Death certificates and a death certificate-derived national database were the sources of cause-of-death infor- mation (see Chapters 4 and 8~. In the study's primary analyses, we examined the numbers and timing of deaths from any cause, any malignancy, and leukemia in the two groups. Additional analytic work involved the use of more detailed, though still broad, cause-of-death categories and the exploration of characteris- tics of the participation experience for evidence consistent with a radiation- caused effect (see Chapter 11~. Initial plans to examine dose-response relation- ships were changed when a working group2 formed by the study's advisory committee determined that the available dose data were inappropriate for use in individual-level epidemiologic analyses (see Chapter 7 and Appendix A). The report contains a brief overview of other types of studies of radiation exposure and effects on human health (Chapter 2~; a description of the U.S. nu- clear test program in general and the five series that are the focus of this study (Chapter 3~; other methodologic issues (Chapters 4 through 8~; the analysis structure (Chapter 9~; description of the participant and referent cohorts (Chapter 10~; the analytic findings (Chapter 11~; and our discussion of these findings (Chapter 12~. Appendixes contain technical detail not essential to understanding the study but of interest to some readers and useful for documentation purposes. 2John Till, Ph.D., served as chair of the dosimetry working group, which included one other oversight committee member (Clarice Weinberg, Ph.D.) and three external dosimetry experts (F. Owen Hoffman, Ph.D.; Keith J. Schiager, Ph.D.; and John Taschner).
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